[Federal Register Volume 64, Number 241 (Thursday, December 16, 1999)]
[Rules and Regulations]
[Pages 70181-70184]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-32584]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-328-AD; Amendment 39-11473; AD 99-23-22 R1]
RIN 2120-AA64


Airworthiness Directives; Various Transport Category Airplanes 
Equipped With Mode ``C'' Transponder(s) With Single Gillham Code 
Altitude Input

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment revises an existing airworthiness directive 
(AD), applicable to various transport category airplanes equipped with 
certain Mode ``C'' transponder(s) with single Gillham code altitude 
input. That AD currently requires repetitive tests to detect 
discrepancies of the Mode ``C'' transponder(s), air data computer, and 
certain wiring connections; and corrective actions, if necessary. The 
existing AD is prompted by reports that, during level flight, the 
Traffic Alert Collision Avoidance System (TCAS II) issued false 
advisories that directed the flightcrew to change course and either 
climb or descend. The actions specified by that AD are intended to 
prevent such false advisories due to inaccurate airplane altitude 
reporting, which could result in the flightcrew deviating the airplane 
from its assigned flight path and a possible mid-air collision. This 
new action revises certain compliance times and limits the 
applicability of the existing AD.

DATES: Effective November 29, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before February 14, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-328-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    Information pertaining to this amendment may be obtained from or 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Ave, 
SW., Renton, Washington 98055-4056.

FOR FURTHER INFORMATION CONTACT: Peter Skaves, Aerospace Engineer, 
Airplane and Flight Crew Interface Branch, ANM-111, FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington

[[Page 70182]]

98055-4056; telephone (425) 227-2795; fax (425) 227-1320.

SUPPLEMENTARY INFORMATION: On November 4, 1999, the FAA issued AD 99-
23-22, amendment 39-11418 (64 FR 61493, November 12, 1999), applicable 
to various transport category airplanes equipped with certain Mode 
``C'' transponder(s) with single Gillham code altitude input. That AD 
requires repetitive tests to detect discrepancies of the Mode ``C'' 
transponder(s), air data computer, and certain wiring connections; and 
corrective actions, if necessary. That action was prompted by reports 
that, during level flight, the Traffic Alert Collision Avoidance System 
(TCAS II) issued false advisories that directed the flightcrew to 
change course and either climb or descend. The actions required by that 
AD are intended to prevent such false advisories due to inaccurate 
airplane altitude reporting, which could result in the flightcrew 
deviating the airplane from its assigned flight path and a possible 
mid-air collision.

Actions Since Issuance of Previous Rule

    Since the issuance of AD 99-23-22, the FAA has determined that the 
existing AD should be revised as follows:
    1. The applicability section of the existing AD has been revised to 
identify only airplane models used in the same type of operations as 
those involved in the reported incidents of reduced airplane 
separation. Specifically, the applicable airplane models have been 
limited to only those transport category airplanes that can be operated 
for extended periods in level flight cruise at altitudes greater than 
24,000 feet and that are equipped with Mode ``C'' transponder(s) with 
single Gillham code altitude input. As the FAA has not yet determined 
the precise cause of the erroneous Mode ``C'' altitude reporting, 
investigations into the cause of the unsafe condition are continuing. 
The FAA has determined that the applicability of the existing AD should 
be limited to airplanes with more exposure to the potential risks of 
incorrect altitude reporting. Based on the review of the data received 
from these airplane inspections, the FAA may consider future rulemaking 
to expand the applicability of this AD.
    2. A note has been added to the existing AD to clarify that the 
requirements of that AD DO NOT supersede the current airplane Master 
Minimum Equipment List (MMEL) requirements for deferral of repair of 
malfunctioning systems. The existing AD states that any malfunctioning 
Mode ``C'' altitude reporting system is to be repaired prior to further 
flight. Note 3 of this revised AD explains that Mode ``C'' transponder 
altitude reporting systems that have been determined to be 
malfunctioning must be turned off and placarded as inoperative, as 
specified in the MMEL. The airplane may then be operated in accordance 
with the MMEL.
    3. The compliance time for accomplishment of the initial and 
repetitive tests required by paragraph (a) of the existing AD has been 
extended from 45 days to 90 days after the effective date of the 
existing AD. Test results received to date indicate that a substantial 
number of airplanes have already been tested without failures. Based on 
these test results and on the increased awareness of operators using 
Mode ``C'' altitude reporting, the FAA has determined that the risk of 
exposure to incorrect altitude reporting has been sufficiently reduced 
to allow extension of the compliance time for accomplishment of the 
initial and repetitive testing. Extended test intervals also will 
provide additional time for operators required to schedule and execute 
the tests. In addition, the reporting requirement specified in 
paragraph (c) of the existing AD has been extended from 10 days to 20 
days after accomplishment of the initial and repetitive tests required 
by paragraph (a) of the existing AD.
    4. The alternative method of compliance paragraph of the existing 
AD has been revised to identify the Manager, Airplane and Flight Crew 
Interface Branch, Transport Airplane Directorate, as the point of 
contact in lieu of the Manager, Seattle Aircraft Certification Office.

Explanation of Requirements of Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of this same type design, this AD 
revises AD 99-23-22 to continue to require repetitive tests to detect 
discrepancies of the Mode ``C'' transponder(s), air data computer, and 
certain wiring connections; and corrective actions, if necessary. This 
action revises certain compliance times and limits the applicability of 
the existing AD. This AD also includes a note which describes 
provisions for continued operation of the airplane in accordance with 
the provisions and limitations specified in the operator's FAA-approved 
Master Minimum Equipment List (MMEL).

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NM-328-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect on the States, on the relationship between the national 
Government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    The FAA has determined that this regulation is an emergency 
regulation

[[Page 70183]]

that must be issued immediately to correct an unsafe condition in 
aircraft, and that it is not a ``significant regulatory action'' under 
Executive Order 12866. It has been determined further that this action 
involves an emergency regulation under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979). If it is determined that 
this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, may 
be obtained from the Rules Docket at the location provided under the 
caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-11418 (64 FR 
61493, November 12, 1999), and by adding a new airworthiness directive 
(AD), amendment 39-11473, to read as follows:

099-23-22  R1 Transport Category Airplanes: Amendment 39-11473. 
Docket 99-NM-328-AD. Revises AD 99-23-22, Amendment 39-11418.

    Applicability: Transport category airplanes, as listed below, 
certificated in any category, equipped with any Mode ``C'' 
transponder with single Gillham code altitude input, including, but 
not limited to, the transponder part numbers listed below. Whether a 
Mode ``C'' transponder has a single Gillham code altitude input may 
be determined by reviewing the transponder installation 
instructions.

Airplane Models

Airbus Industrie
    A300
    A310
British Aerospace
    BAe Avro 146-RJ
    BAe ATP
Fokker
    F28 Mark 0070
    F28 Mark 0100
    F28 Mark 1000-4000
Lockheed
    L-1011 TriStar
    L-188 Electra
CASA
    CN-235
Dassault Aviation
    Mystere Falcon 50
    Mystere Falcon 900
    Mystere Falcon 200
    Fan Jet Falcon Series G
Boeing (MDC)
    DC-10-30
    DC-10-40
    DC-9
    DC-9-81
    DC-9-82
    DC-9-83
    DC-9-87
    Boeing 707
    Boeing 727
    Boeing 737
    Boeing 747
Bombardier
    CL-215-1A10
    CL-215-6B11
    CL-600-1A11
    CL-600-2A12
    CL-600-2B16
Gulfstream
    G1159 (G-II)
    G-1159A (G-III)
    G-IV

Mode ``C'' Transponder Part Numbers:

Rockwell Collins
    622-2224-001
    622-2224-003
    522-2703-001
    522-2703-011
    787-6211-001
    787-6211-002
Bendix
    066-1056-00
    066-1056-01
    066-1123-00
    2041599-6508
Wilcox
    97637-201
    97637-301
IFF
    APX-100
    APX-101

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (d) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent false Traffic Alert Collision Avoidance System (TCAS 
II) advisories due to inaccurate airplane altitude reporting, which 
could result in the flightcrew deviating the airplane from its 
assigned flight path and a possible mid-air collision, accomplish 
the following:

Repetitive Tests

    (a) Within 90 days after November 29, 1999 (the effective date 
of AD 99-23-22, amendment 39-11418): Perform the test procedures 
specified in paragraphs (a)(1) through (a)(9) of this AD to detect 
any discrepancies of the Mode ``C'' transponder(s), air data 
computer (ADC), or Gillham wiring connections, in accordance with 
the applicable ADC and Mode ``C'' transponder component maintenance 
manuals and airplane maintenance manual. Repeat the test procedures 
thereafter at intervals not to exceed 90 days.
    (1) Connect an air data test set to the Captain's (No. 1) Pitot/
Static system.
    (2) In the airplane flight deck, select Mode ``C'' transponder 
(1), or left Mode ``C'' transponder, depending on airplane flight 
deck configuration, and select ADC source (1).
    (3) Select the air data test set to the following altitude 
reporting values:

1,000 feet;
4,100 feet;
15,700 feet; and
31,000 feet.

    (4) For each selected altitude, verify that the Mode ``C'' 
altitude reporting is within tolerance (+/-125 feet), and record the 
altitude output as follows:
1,000 feet (+/-125 feet);
4,100 feet (+/-125 feet);
15,700 (+/-125 feet); and
31,000 feet (+/-125 feet).

    (5) In the airplane flight deck, select ADC source (2) and 
repeat paragraphs (a)(3) and (a)(4) of this AD.
    (6) In the airplane flight deck, select Mode ``C'' transponder 
(2), or the right Mode ``C'' transponder, depending on airplane 
flight deck configuration, select ADC source (1), and repeat 
paragraphs (a)(3) and (a)(4) of this AD.
    (7) In the airplane flight deck, select ADC source (2) and 
repeat paragraphs (a)(3) and (a)(4) of this AD.
    (8) Connect an air data test set to the Captain's (No. 2) Pitot/
Static system.
    (9) Repeat paragraphs (a)(2) through (a)(7) of this AD.

    Note 2: The tests required by paragraph (a) of this AD examine 
the three primary sources of inaccurate airplane altitude reporting. 
These three sources are: ADC's, Mode ``C'' transponders, and the 
Gillham wiring connections between the ADC and Mode ``C'' 
transponder.

Corrective Actions

    (b) Except as permitted by the Master Minimum Equipment List 
(MMEL): If any discrepancy is detected during any test required by 
paragraph (a) of this AD: Prior to further flight, repair in 
accordance with the applicable ADC and Mode ``C'' transponder 
component maintenance manual and airplane maintenance manual. If the 
repair information is not available in the applicable manual, except 
as permitted by the MMEL, prior to further flight, repair in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate.

    Note 3: The airplane may be operated in accordance with the 
provisions and

[[Page 70184]]

limitations specified in the FAA-approved MMEL, provided that only 
one Mode ``C'' transponder on the airplane is inoperative.

Reporting Requirement

    (c) Within 20 days after accomplishing the initial and 
repetitive tests required by paragraph (a) of this AD, submit a 
report of the inspection and test results (both positive and 
negative findings) to: Peter Skaves, Aerospace Engineer, Airplane 
and Flight Crew Interface Branch, ANM-111, FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; 
fax (425) 227-1320. The test results must include the Mode ``C'' 
transponder(s) and ADC part number(s), and must specify if any 
discrepancies of the Gillham wiring connections were detected, and 
if corrective action was required. Information collection 
requirements contained in this regulation have been approved by the 
Office of Management and Budget (OMB) under the provisions of the 
Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have 
been assigned OMB Control Number 2120-0056.

Alternative Methods of Compliance

    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Airplane and Flight Crew Interface 
Branch, ANM-111, FAA, Transport Airplane Directorate. Operators 
shall submit their requests through an appropriate FAA Principal 
Maintenance or Avionics Inspector, who may add comments and then 
send it to the Manager, ANM-111.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Manager, ANM-111.

Special Flight Permits

    (e) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (f) The effective date of this amendment remains November 29, 
1999.

    Issued in Renton, Washington, on December 10, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-32584 Filed 12-15-99; 8:45 am]
BILLING CODE 4910-13-P